Air lift



May 30, 1933 l.. c. STUKENBORG 1,912,103

AIR LIFT Filed March 26, 1931 Jaa/5 fare/vaya Patented May 30, 1933UNITED STARS LoUrs c. srnnnnnone, or MEMPHIS, TENNESSEE AIR nir'rApplication filed March 28, 1931. Serial No. 525,395.

This invention has reference to a lift or jack which is operated bycompressed air through the agency of a liquid.

The objects of the invention are to provide 5 means whereby a liftplunger' is raised and supported through the medium of a liquid to whichpressure is applied by compressed air; and

To provide means for automatically rel@ leasing the air pressure at apredetermined level whereby the amount of lift is limited and at thesame time the actuating pressure is released on the raising liquid.

The means by. which the foregoing and other objects are accomplished andthe manner of their accomplishment will readily be understood from thefollowing specification on reference to the accompanying drawing, inwhich:

o Fig. 1 is a sectional elevation on the center line of a jack cylinderand of a compressedair tank associated therewith;

Fig. 2 is a plan view of the tank and the piping therefrom together witha diagrammatic view of an air compressor and an air reservoir associatedwith such air tank.

Referring now to the drawing, in which the various parts are indicatedby numerals,

is a vertically disposed cylinder, prefer- 3 ably sunk below the groundlevel, in which is disposed a plunger 11 on the upper end of which ismounted a head 12 and such other -load carrying members as may bedesired.

r 13 is a pressure tank. 14 is an air compressor u and 15 an airreservoir. 16 is a pipe leading from the air reservoir through athree-way valve, preferably a stop and waste cock 17,

into the top of the tank 13. 18 is an air release valve discharging fromthe top of the tank 13, which valve is closed by the upward,

or opened by the downward movement of a float 19 which within limitsfollows the level of the liquid 20 within the tank.

Leading from the bottom of the tank so that it is denitely below theliquid level is a pipe 21 which discharges into the cylinder 10. 22 is aby-pass pipe leading horizontally from this pipe back into the tank 13.23 is a check valve in the line 21 between the tank and the by-passline, this check valve permitting flow from the Vtank but preventingreturn flow thereto. 24 is a lever actuated gate or throttle valve, inthe line 21 between the check valve Vand the cylinder and 25 is a ,valvein the by-pass line 22. u 1

In filling the tank the valves 24 and 25 are closed and such amount ofliquid, preferably oil placed in the tank 13 as is necessary to raisethe float 19 to a level which will just close the release valve 18. Suchadditional amount of oil is then added in the tank 13 as will be neededto raise the plunger 11 to desired height, this additional oil holdingthe release valve tightlyv closed. j

In using the device compressed.V air from the reservoir v15 is admittedto the tank 13 by opening the cock 17 establishing pressure on the oiltherein. The throttle valve 24CV is opened and the oil caused to iiow tothe cylin- ,der 10 by pressure of the air on the o il within the tank,thus raising the plunger.

' Air pressure is meanwhile maintained in the tank by the compressor.Rise of the plunger may be checked at any point by closing the throttlevalve, but in case such closure is neglected, lowering of the oil andthe float therein will open the release valve 18 and allow escape of theair pressure in the tank, and consequent checking of the plunger lift,but such air escape will not allow drop 's6 of the plunger since returniiow of oil is presented by the check valve.

At such time the compressed air cock should' be closed and air escapefrom the tank allowed there also, but air escape is posi'- tive 'as soonas` the speed of air release is greater than the inflow of compressedair, whether the air cock closure be made or not. As soon as the aircock is cut off escape of air from the tank relieves pressure on the oilist and such pressure drops to that of the atmosphere. The oil which haspassed the check valve 23 is retained in the cylinder and the plunger isnecessarily held in raised position irrespective of such release of airpressure fe' in the tank. To lower the plunger the bypass valve 25 isopened and flow established through the by-pass line into the tank, thisY flow acting in such case against atmospheric pressure only and beingtherefore controlled solely by the amount of opening by the valve.

Having described my invention, what I claim is l. In a liftingmechanism, the combination, with a cylinder, a plunger therein, a closedtank for liquid, a pipe line connecting said tank with said cylinder,and ay pipe leading into said tank from a source of compressed air, ofan air vent for said tank controlled by a float valve, the float havinga level at and above which said vent is closed, and below which saidvent remains open; and means whereby the extent of lifting movement ofsaid plunger may be limited by limiting the volume of liquid initiallyplaced in said tank above the level at which said vent valve is closedby said float.

2. In lifting mechanism, the combination, with a cylinder, a plungertherein, a closed tank for liquid, a pipe line connecting said tank withsaid cylinder, and a pipe leading into said tank from a source ofcompressed air, of an air vent for said tank controlled by a floatvalve, there being a predetermined level for the float at and abovewhich said vent is closed, and below which said vent remains open; avalve for control ling the flow of compressed air to said tank; andmeans whereby the lifting movement of said plunger terminates when saidoat descends below said predeterminedk level.

3. In lifting mechanism, the combination, i

with a cylinder, a plunger therein, a closed tank for liquid, a pipeline connecting said tank with said cylinder, and a pipe leading intosaid tank from a source of compressed air, of an air vent for said tankcontrolled by a float valve which is closed when the float is at orabove a predetermined level, and remains open when the float is belowsaid level; a by-pass from said pipe line to said tank; a check valve insaid pipe line between said by-pass and said tank; and a three-way valvein said compressed-air line-whereby, during lowering movement of saidplunger the oil in said cylinder is by-passed back into said tank, airmeanwhile being vented from said tank through said vent and saidthree-way valve until the liquid in said tank raises the floatsuiiiciently to close the vent valve, after which air continues to bevented through said three-way valve.

In testimony whereof I hereunto affix my signature.

LOUIS C. STUKENBORG.

